Design of silt dam for controlling negative impacts of river siltation
Siltation involves the accumulation of sediment over a considerable period of time and this may occur in closed system like leaching tanks. Most mining company in Rwanda experience siltation problems during mineral processing. This research project examine the potential causes and possible mitigation measure of River siltation. Particle size analysis, slurry settling rate test and agitation efficiency analysis were used to identify the factor that cause siltation, the result from the study indicate that the use of hydraulic mining method and traditional mineral processing method like ground sluicing, panning and washing ore in trenches and finally the water mixed with silts flow directly into the river, this cause a problem to the surrounding environmental degradation. Those problems include the change in river direction, soil erosion, increase flooding in the river, disturbance of aquatic animals, and also the most issues of those silts damage Hydro-Electric power station build on NYABARONGO River. The objectives of this research project is to determine the source and the potential impact of silts to the environment, identify the quantity of silts disposed into NYABARONGO River and design of silt dam for controlling river siltation. My project was to design silt dam to capture those silt from mineral processing in order to prevent those negative impact caused by silts. According to the result of our study we recommend to KNM Combines Ltd to build silt dams in order to reduce environment degradation caused by silts and implement this project in order to elaborate temporary inactive of the company by government due to the silts damage hydroelectric power station build on Nyabarongo River. When this taken into consideration our environment will be safe and sustainable.
Keywords: mining, river, siltation, silt dams, environmental degradation